Many different types of manufacturing plants operate around the clock without shutting down except for emergency situations or infrequent, scheduled, long-term maintenance. Reasons for continuous operation include cost of shut down and restart, and potential impacts on quality of products until steady state is reached after restart. Semiconductor fabricating plants are an example of such a typically continuously-operating manufacturing facility. Because of continuous operation, it can at times be difficult or costly to improve, modify or otherwise change configurations in such facilities.
When a continuously-operating fabricating plant uses ducts or pipes for conveying flowable materials, which may include gases or liquids, sometimes modifications can be made by “hot tapping” into a pipe or duct to add a new branch line without the need to shut down. However, hot tapping in semiconductor fabricating plants presents special challenges due to the corrosive nature of the gases conveyed within the duct work and the properties of the corrosion-resistant materials, such as fluoropolymer coatings, used to protect the duct work. Difficulties include minimizing damage to the protective coating, the adhesion-resistant properties of the coatings and the fact that even with carefully controlled processes, hot tapping into a duct creates a cut edge of the duct exposed to the corrosive materials transported therethrough.
Various solutions have been proposed in the art for hot tapping coated ductwork transporting highly corrosive materials, including applying new protective coating material to the cut edges created during the hot tap process. However, available solutions are not always satisfactory due to difficulties in applying new coatings under field operating conditions, while maintaining system pressure, often in awkward positions where visibility of the areas to be treated is limited or impossible.